Synthesis and optical characterization of lanthanide-doped colloidal Ga2O3 nanoparticles

•Synthesis of colloidal nanosized Ga2O3 particles.•Tunable emission by incorporating different lanthanide ions inside the Ga2O3 host.•Z-scan measurements of two-photon absorption cross-section of Ga2O3 nanoparticles.

We demonstrate the use of thermal decomposition reaction to obtain Ga2O3 nanoparticles with average size around 5 nm. The obtained nanoparticles presented a good colloidal stability and high optical transparency. We were also able to incorporate Eu3+ and Tb3+ ions inside the crystal host. The synthesized nanomaterials exhibited dual mode emission upon UV excitation, consisting of a broad band in the blue region and a characteristic series of sharp lines. The former resulted from donor-acceptor pairs recombination in Ga2O3 host, while the latter from 4f-4f electronic transitions in lanthanide ions. For fuller optical characterization of the obtained nanoparticles, we have performed wide wavelength range Z-scan studies, and calculated the values of nonlinear absorption cross-sections. Gallium (III) oxide nanoparticles showed two-photon absorption in the range between 500 nm and 700 nm, with molecular weight scaled nonlinear optical parameters exceeding the values for other lanthanide-doped nanoparticles of similar size.

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